The general object of metrology is to monitor one or more selected physical phenomena to permit a record of monitored events. Such basic purpose of metrology can be applied to a variety of metering devices used in a number of contexts. One broad area of measurement relates, for example, to utility meters. Such role may also specifically include, in such context, the monitoring of the consumption or production of a variety of forms of energy or other commodities, for example, including but not limited to, electricity, water, gas, or oil.
More particularly concerning electricity meters, mechanical forms of registers were historically used for outputting accumulated electricity consumption data. Such an approach provided a relatively dependable field device, especially for the basic or relatively lower level task of simply monitoring accumulated kilowatt-hour consumption. Such basic mechanical form of register was typically limited in its mode of output, so that only a very basic or lower level metrology function was achieved. Subsequently, electronic forms of metrology devices began to be introduced, to permit relatively higher levels of monitoring, involving different forms and modes of data.
In the context of electricity meters specifically, for a variety of management and billing purposes, it has become desirable to obtain more sophisticated usage data. Solid state devices provided on printed circuit boards, for example, utilizing programmable integrated circuit components, have provided effective tools for implementing many of such higher level monitoring functions desired in the electricity meter context. In addition to the beneficial introduction of electronic forms of metrology, a variety of electronic registers have been introduced with certain advantages. Still further, other forms of data output have been introduced and are beneficial for certain applications, including wired transmissions, data output via radio frequency transmission, pulse output of data, and telephone line connection via such as modems and/or wireless (such as cellular) linkups.
The advent of such variety and alternatives has often required utility companies to provide data collection mechanisms wherein appropriate data may be collected in environments that are increasingly hostile to such data collection. For example, electrical noise emanating from sources near electricity meter sensing functions may constitute a source of error in collected data. Likewise, different types of metering and/or monitoring components may have various thermal sensitivities, accounting for which may become more problematic as the complexity of associated circuitry and thermal environment fluctuations increase.
Electricity meters typically include input circuitry for receiving voltage and current signals or levels at the electrical service. Input circuitry of whatever type or specific design for receiving the electrical service current signals is referred to herein generally as current acquisition circuitry, while input circuitry of whatever type or design for receiving the electrical service voltage signals is referred to herein generally as voltage acquisition circuitry. There are additional issues related to the measurement of voltage and current that present their own problems. One such problem relates to the stability and reliability of the measured quantities during operation over a dynamic range of conditions, including ranging thermal conditions. Under more or less normal operational conditions, thermal conditions may vary significantly, and for a variety of reasons. Due to such fact, it can be difficult to use simple, reliable approaches for accommodating and/or compensating for, or otherwise preventing deleterious measurement effects due to, varying thermal conditions.
Hall sensors are generally known and often used to measure magnetic fields in a wide variety of applications such as in position sensing, contactless current sensing, and in electricity metering. In general, and as is well known to those of ordinary skill in the art, a Hall sensor is a device with at least four contacting electrodes. When biased with a current (Ibias) through two of such electrodes, a Hall sensor delivers between its other two electrodes a voltage that is proportional both to the component of the magnetic field perpendicular to the current trajectory, and to the value of the biasing current (Ibias).
It is a common practice that many Hall sensors are fabricated using thin-film technologies, at least in some respects similar to techniques and technologies as used with semiconductor processing. However, because of changes in electron population in the active area of such sensors, the magnetic sensitivities of such Hall sensors tends to be temperature dependent.
In view of the foregoing, it is desired to provide a metrology technology that permits the collection of accurate data regardless of the environment in which the metrology device is installed, and irrespective of the load under which the supply source operates, i.e., to provide a metrology device which is universally applicable with respect to environment, particularly as to a varying thermal environment. In the instance of an electricity meter which makes use of Hall sensor technology, it is desired to provide method and apparatus for controlling the sensitivity temperature drift of such Hall sensor technology at any current bias (Ibias) chosen therefore.
While various aspects and alternative embodiments may be known in the field of utility metering, no one design has emerged that generally encompasses the above-referenced characteristics and other desirable features associated with utility metering technology as herein presented.